Horton

Re: proposal: schema variables

jian he <jian.universality@gmail.com>

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From: jian he <jian.universality@gmail.com>
To: Pavel Stehule <pavel.stehule@gmail.com>
Cc: Dmitry Dolgov <9erthalion6@gmail.com>, Laurenz Albe <laurenz.albe@cybertec.at>, Erik Rijkers <er@xs4all.nl>, Michael Paquier <michael@paquier.xyz>, Amit Kapila <amit.kapila16@gmail.com>, DUVAL REMI <REMI.DUVAL@cheops.fr>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2024-12-07T02:13:26Z
Lists: pgsql-hackers, pgsql-performance

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

  1. Move WAL sequence code into its own file

  2. Add ExplainState argument to pg_plan_query() and planner().

  3. Don't include access/htup_details.h in executor/tuptable.h

  4. Refactor to avoid code duplication in transformPLAssignStmt.

  5. Avoid including commands/dbcommands.h in so many places

  6. Restrict psql meta-commands in plain-text dumps.

  7. Split func.sgml into more manageable pieces

  8. Fix squashing algorithm for query texts

  9. EXPLAIN: Always use two fractional digits for row counts.

  10. Preliminary refactoring of plpgsql expression construction.

  11. plpgsql: pure parser and reentrant scanner

  12. Add some sanity checks in executor for query ID reporting

  13. Fix misleading error message context

  14. Add macros for looping through a List without a ListCell.

On Thu, Dec 5, 2024 at 2:52 PM Pavel Stehule <pavel.stehule@gmail.com> wrote:
>
> Hi
>
> only rebase

hi.
disclaimer, i *only* applied
v20241205-0001-Enhancing-catalog-for-support-session-variables-and-.patch.

create variable v2 as text;
alter variable v2 rename to v2;
ERROR:  session variable "v2" already exists in schema "public"

the above is  coverage tests for report_namespace_conflict:
        case VariableRelationId:
            Assert(OidIsValid(nspOid));
            msgfmt = gettext_noop("session variable \"%s\" already
exists in schema \"%s\"");
            break;

create type t1 as (a int, b int);
CREATE VARIABLE var1 AS t1;
alter type t1 drop attribute a;
should "alter type t1 drop attribute a;" not allowed?


GetCommandLogLevel also needs to deal with  case T_CreateSessionVarStmt?


there are no regress tests for the change we made in
find_composite_type_dependencies?
It looks like it will be reachable for sure.


CreateVariable, print out error position:
    if (get_typtype(typid) == TYPTYPE_PSEUDO)
        ereport(ERROR,
                (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                 errmsg("session variable cannot be pseudo-type %s",
                        format_type_be(typid)),
                 parser_errposition(pstate, stmt->typeName->location)));

Alvaro Herrera told me actually, you don't need the extra parentheses
around errcode.
so you can:
    if (get_typtype(typid) == TYPTYPE_PSEUDO)
        ereport(ERROR,
                errcode(ERRCODE_WRONG_OBJECT_TYPE),
                errmsg("session variable cannot be pseudo-type %s",
                        format_type_be(typid)),
                parser_errposition(pstate, stmt->typeName->location))


pg_variable_is_visible seems to have done twice the system cache call.
maybe follow through with the pg_table_is_visible, pg_type_is_visible
code pattern.


IN src/bin/psql/describe.c
+ appendPQExpBufferStr(&buf, "\nWHERE true\n");
this is not needed?
------------------------------------------------
some of the `foreach` can change to foreach_oid, foreach_node
see: https://git.postgresql.org/cgit/postgresql.git/commit/?id=14dd0f27d7cd56ffae9ecdbe324965073d01a9ff
------------------------------------------------
doc/src/sgml/ref/create_variable.sgml
<programlisting>
CREATE VARIABLE var1 AS date;
LET var1 = current_date;
SELECT var1;
</programlisting>

v20241205-0001-Enhancing-catalog-for-support-session-variables-and-.patch
alone cannot do `LET var1 = current_date;`, `SELECT var1;`
maybe the following patch can do it. but that makes
we cannot commit
v20241205-0001-Enhancing-catalog-for-support-session-variables-and-.patch
alone.
------------------------------------------------
since CREATE VARIABLE is an extension to standard, so in create_schema.sgml
Compatibility section,
do we need to mention CREATE SCHEMA CREATE VARIABLE is an extension
from standard
?
-----------------------------------------------

/*
 * Drop variable by OID, and register the needed session variable
 * cleanup.
 */
void
DropVariableById(Oid varid)
i am not sure of the meaning of "register the needed session variable cleanup".